1. Field of the Invention
The present invention relates to friction stir welding. More particularly, the present invention relates to using friction stir welding to repair weld defects and to help avoid weld defects in intersecting welds in crack-sensitive material.
Even more particularly, the invention relates to hybrid friction stir welding (FSW) as a defect repair technique and microstructure modification approach to intersection weld crack mitigation for 2195 Al--Cu--Li VPPA/SPA (variable polarity plasma arc/soft plasma arc) weldments.
2. General Background of the Invention
Friction stir welding (FSW) is a solid state joining process developed by The Welding Institute (TWI), Cambridge, England and described in U.S. Pat. No. 5,460,317, incorporated herein by reference. Also incorporated herein by reference are U.S. Pat. No. 5,718,366 and all references disclosed therein.